Method for encoding/decoding image, and device therefor

Abstract

Provided is an image decoding method including: determining at least one prediction block included in a current picture from among pictures forming an image; determining a first motion vector related to a current prediction block from among the at least one prediction block; determining a first reference block included in a first reference picture, based on the first motion vector; determining a second reference block included in a second reference picture, based on a location of the first reference block; and decoding the current picture by performing inter prediction on the current prediction block by using at least one of the first reference block and the second reference block, wherein the second reference picture includes a prediction value of the first reference picture. Also, provided are an image decoding apparatus performing the image decoding method, and an image encoding method and apparatus corresponding to the image decoding method and apparatus.

The invention claimed is: 
     
       1. An image decoding method comprising:
 determining a first motion vector related to a current prediction block; 
 determining a first reference block included in a first reference picture, based on the first motion vector; 
 determining a second reference block included in a second reference picture, based on a location of the first reference block; 
 determining a first weight and a second weight by using a neighboring sample value of the first reference block and a neighboring sample value of the second reference block, 
 determining a third reference block by applying the first weight and the second weight respectively to the first reference block and the second reference block; and 
 decoding the current picture by performing inter prediction on the current prediction block by using at least one of the first reference block, the second reference block, and the third reference block, 
 wherein the second reference picture comprises a prediction value of the first reference picture. 
 
     
     
       2. The image decoding method of  claim 1 , wherein the second reference picture comprises a sample obtained by performing motion estimation and motion compensation during an encoding process of the first reference picture. 
     
     
       3. The image decoding method of  claim 1 , wherein the decoding of the current picture comprises:
 determining at least one reference block used to perform the inter prediction, based on reference block information obtained from a bitstream; and 
 performing the inter prediction by using the at least one reference block, 
 wherein the reference block information indicates whether the second reference blocks is used to perform the inter prediction on the current prediction block. 
 
     
     
       4. The image decoding method of  claim 3 , wherein the determining of the at least one reference block comprises, when the reference block information indicates that the inter prediction is performed via a prediction method using the second reference block, determining at least one reference block comprising the second reference block used to perform the inter prediction, based on a pre-determined condition. 
     
     
       5. The image decoding method of  claim 4 , wherein the determining of the at least one reference block based on the pre-determined condition comprises determining whether only the second reference block is used or both the first and second reference blocks are used to perform the inter prediction, based on at least one of a first condition of a difference between the first reference picture and the second reference picture being smaller than a first threshold value and a second condition of a difference between a size of the first motion vector being smaller than a second threshold value. 
     
     
       6. The image decoding method of  claim 1 , wherein the first weight and the second weight are determined by using at least one sample adjacent to a left boundary of the first reference block and at least one sample adjacent to a left boundary of the second reference block. 
     
     
       7. The image decoding method of  claim 1 , wherein the first reference picture and the second reference picture are stored in different buffers. 
     
     
       8. The image decoding method of  claim 1 , wherein the first reference picture and the second reference picture are stored in a same buffer. 
     
     
       9. The image decoding method of  claim 1 , further comprising:
 determining a second motion vector related to the current prediction block; 
 determining a fourth reference block included in a fourth reference picture, based on the second motion vector; and 
 determining a fifth reference block included in a fifth reference picture, based on the fourth reference block, 
 wherein the fifth reference picture comprises a prediction value of the fourth reference picture. 
 
     
     
       10. The image decoding method of  claim 9 , wherein the decoding of the current picture comprises performing bi-directional inter prediction on the current prediction block by using at least one of the first and second reference blocks and at least one of the fourth and fifth reference blocks. 
     
     
       11. An image encoding method comprising:
 determining a first motion vector related to a current prediction block; 
 determining a first reference block included in a first reference picture, based on the first motion vector; 
 determining a second reference block included in a second reference picture, based on a location of the first reference block; 
 determining a first weight and a second weight by using a neighboring sample value of the first reference block and a neighboring sample value of the second reference block; 
 determining a third reference block by applying the first weight and the second weight respectively to the first reference block and the second reference block; and 
 encoding the current picture by performing inter prediction on the current prediction block by using at least one of the first reference block, the second reference block, and the third reference block, 
 wherein the second reference picture comprises a prediction value of the first reference picture. 
 
     
     
       12. An image decoding apparatus comprising:
 a decoder configured to determine a first motion vector related to a current prediction block; and 
 a reference block determiner configured to determine a first reference block included in a first reference picture, based on the first motion vector, determine a second reference block included in a second reference picture, based on a location of the first reference block, determine a first weight and a second weight by using a neighboring sample value of the first reference block and a neighboring sample value of the second reference block, and determine a third reference block by applying the first weight and the second weight respectively to the first reference block and the second reference block, 
 wherein the decoder is further configured to decode the current picture by performing inter prediction on the current prediction block by using at least one of the first reference block, the second reference block, and the third reference block, and 
 wherein the second reference picture comprises a prediction value of the first reference picture.